This invention relates to gas burners, and particularly to gas burner head construction.
Most of the gas burners for currently produced domestic water heaters incorporate a burner head comprising two concave portions secured together. While such heads may differ in some details, generally, a bottom concave portion is centrally apertured to receive a gas-air mixture, the space between the bottom concave portion and a top concave portion provides a venturi, and the peripheral edges of both portions are constructed so as to provide a plurality of outlet ports therebetween for the gas-air mixture. The burner head is usually positioned in axial alignment with the flue portion of the water heater. Such a position enables effective heating of the bottom surface of the water-containing tank and facilitates the exhausting, through the flue portion, of the products of combustion.
The constant demand for improved efficiency of operation of water heaters has generated various changes in construction of the water heater tank. One particularly popular efficiency-improving construction has been the addition of baffling means in the flue portion. Such baffling means slows down the rate at which the hot flue gases are permitted to exhaust. This results in increased heat transfer from the hot flue gases to the walls of the flue portion. Since the outside walls of the flue portion are in contact with the water to be heated, such baffling means thus increases the over-all efficiency of the water heater in that more of the energy content of the burner flame is utilized to heat the water.
Such baffling means, however, also reduces the temperature of the flue gases. Since the flue gases contain water vapor, a sufficiently low flue gas temperature will cause the water vapor to condense on the interior walls of the flue portion. Condensate then creeps downwardly along the flue portion and drips onto the axially aligned burner head. Since the burner head is concave, water accumulates therein. After sufficient water has accumulated, it begins to creep over the peripheral edge of the top concave portion and into the outlet ports, causing the burner flame to be distorted or even extinguished at one or more outlet ports.